The present invention relates to a master gear. More particularly, the present invention relates to a master gear for use in gear checking, that uses forced harmonic vibration.
Gears, particularly those used in gear systems for automotive use, e.g., automotive transmissions, are often checked to assure that the gears are properly formed. That is, the gears are checked to assure that they are formed without burrs, grind marks, and the like. Other imperfections include plus material in tooth formation, waviness and improper finish and imperfections in the involute. These imperfections can cause vibration and “noise” that can be transferred to the vehicle which can result in vehicle vibration, noise and reduced life of the driving or driven components.
The gears are checked in a dynamic environment, that is with the gear rotating at some predetermined speed. The gear being checked, or production gear, is driven and meshes with a reference or standard gear, or master gear. In a typical arrangement, the production gear is driven (i.e., applies a driving torque) and the master gear is configured similar to the mating gear of the gear being checked. The master gear has a resistance applied to simulate an actual operating environment. Imperfections in the gear are typically identified at the normal frequency of the gear or at a harmonic of that frequency.
In order to determine whether there are imperfections in the production gear, external devices or sensors (such as accelerometers) are used to monitor the vibrations induced in the system by the rotating gears. In a typical arrangement, measurements are taken at the gear being tested (on the testing structure adjacent to the gear) and at the master gear, for example on the master gear spindle.
It has, however, been found that at times, there are vibrations induced in the system that are above a desired or target level, but that do not exceed a threshold level indicating an imperfection in the gear. Essentially, although the checking system performs satisfactorily, it may not be sufficiently sensitive (e.g., induce sufficient energy to the tested gear) to identify imperfections that otherwise should be corrected.
Accordingly, there is a need for a gear checking system and master gear that are sufficiently sensitive to identify otherwise acceptable imperfections in gears. Desirably, such a master gear induces exaggerated energy levels in gears that exhibit imperfections, but does not exhibit such an exaggeration in gears that exhibit normal or within range vibration.